1. Field of the Invention
The present invention relates to an ink jet device, and more particularly to an ink jet device that prevents the formation of bad ink patterns as well as improving the life span of the ink jet device.
2. Description of the Related Art
An ink jet device is a printing device that sprays ink through a plurality of nozzles by pressing the ink using a piezoelectric device or a heater, thereby printing a letter or picture on a printing paper. The ink jet device sprays ink, including dye ink, organic pigment, or carbon black through the nozzle in order to print a letter or picture while operating a printing head having a plurality of nozzles, thereby forming a minute dot in a paper. And, a set of minute dots records the letter or picture on the paper.
Recently, it has been proposed to form wire lines and a spacer for a liquid crystal display panel by use of the ink jet device, especially, an ink jet device that uses a piezoelectric device that sends out ink and does not require a heating process.
Further, the ink jet device that forms the wire line, spacer, etc. of the flat panel display panel forms the wire line and spacer by spraying material such as minute metal particles for the wire line and ball spacers for the spacers of the flat panel display panel. The discharged material includes solvent besides the minute metal particles and ball spacers that are the materials for forming the patterns of the wire line and spacer. The material for forming the patterns is mixed into the solvent, thereby being sprayed through the ink jet device.
In the case where the material for forming the patterns is the minute metal particle, the discharged matter of the ink jet device is composed of the mixture of the solvent and the minute metal particle of 1-100 nm. In the case where the material for forming the patterns is the ball spacer, the discharged material of the ink jet device is composed of the mixture of the solvent and the ball spacer of 10 μm or less. To describe more specifically about the discharged material for forming the spacer, the ball spacer is made from a material of polystyrene, etc of 3-15 μm in diameter, and the solvent mixed with the ball spacer may include water, IPA (isopropyl alcohol), glycerol, etc.
The discharged material is sprayed through the nozzles, thereby producing a desired pattern. The desired pattern is directed by a host computer (not shown) included in the ink jet device.
FIG. 1 is a diagram briefly representing ink jet device of the related art, and an area ‘A’ of FIG. 1 is illustrated for explaining an ink jet head more specifically.
Referring to FIG. 1, the ink jet device for spraying the minute metal particles or the ball spacers includes an ink jet head 1 having a plurality of nozzles 9 that discharges a material, and a storing part 11 that stores the discharged material.
Further, the ink jet device further includes: a pump 13 and a circulation path 23 that are formed between the storing part 11 and the ink jet head 1 in order to prevent precipitation and cohesion of the ball spacers or the minute metal particles of the discharged material stored at the storing part 11; first to third supply tubes 21, 22, 24 providing a passage through which the discharged material or cleaning water is supplied; a cleaning water supplier 15 that supplies the cleaning water for cleaning impurities or the precipitated minute particles of the inner part of the supply tube or the ink jet head part 1; a discharging part 17 for sending out the cleaning water including the precipitated minute particles; and first and second valves 31, 33 for controlling the flow of the cleaning water or the discharged material between the first to third supply tubes 21, 22, 24.
The storing part 11 acts to store the discharged material for the pattern to be formed.
The storing part 11 is connected to the first supply tube 21 that provides a passage through which the discharged material may move, and the first supply tube 21 has the second valve 33 that determines whether or not the discharged material is discharged through the head part 1.
The discharged material stored at the storing part 11 moves to the ink jet head 1 along the first supply tube 21 and the third supply tube 24 that connects the first supply tube 21 and the ink jet head 1 when only the second valve 33 is opened.
The ink jet head 1 further includes a collecting and delivering part 3 connected to the third supply tube 24 to accumulate the discharged material supplied from the storing part 11; a plurality of chambers 5 connected to the collecting and delivering part 3 to receive the discharged material accumulated at the collecting and delivering part 3; and a plurality of nozzles 9 connected to a plurality of chambers 5 to form a pattern by spraying the discharged material.
The collecting and delivering part 3 acts to send out the discharged material transmitted from the third supply tube 24.
The chambers 5 act to cause the discharged material supplied from the collecting and delivering part 3 to be sprayed through the nozzle 9. The piezoelectric device is adjacent to each of the chambers 5 in order to spray the discharged material through the nozzle 9. Each of the piezoelectric devices is controlled by a host computer. In the ink jet device, when the piezoelectric device operates according to the control signal of the host computer, pressure is applied to the inside of the chamber 5, and the discharged material inside of the chamber 5 is sprayed through the nozzle 9 by the pressure. The ink jet device may form a desired pattern through the sprayed discharged material, and the operation of the piezoelectric device is controlled in accordance with the desired pattern.
On the other hand, the discharged material stored at the storing part 11 includes minute particles such as minute metal particles or ball spacers, thus if a long time lapses, the minute particles included in the discharged material might be precipitated or cohered. In order to prevent the precipitation and cohesion of the minute particles, the circulation path 23. and the pump 13 are connected between the first supply tube 21 and the storing part 11.
The circulation path 23 is a stirring means which makes it possible for the discharged material stored at the storing part 11 to flow all the time. The minute particles included in the discharged material are prevented from precipitating or cohering by the circulation path 23 acting as a stirring means.
The pump 13 acts to provide a driving force to the discharge material so that the discharged material stored at the storing part 11 moves through the circulation path 23.
Further, when using the ink jet device for a long time, the inside of the head part 1 may be contaminated with the precipitation, cohesion, adherence, etc. of the minute particles included in the discharged material. In order to remove the contaminant, an operator first closes the second valve 33 of the ink jet device and impedes the supply of the discharged material. Then, the operator opens the first valve 31 connected to the cleaning water supplier 15 so that the cleaning water can flow through the second supply tube 22 connected to the first valve 31 and the third supply tube 24 connected to the second supply tube 22. The cleaning water is discharged to the outside by flowing along the collecting and delivering part 3 connected to the third supply tube 24, the chamber 5 connected to the collecting and delivering part 3, and the nozzle 9 connected to the chamber 5 through the third supply tube 24. In this way, the cleaning water discharges the contaminant inside the head part 1 as the cleaning water is discharged to the outside through the head part 1.
In order to make the discharge of the contaminant more effective, the ink jet device might further include a discharging part 17 including a discharging tube 25 connected to the head part 1 and a third valve 35 connected to the discharging tube 25.
As described above, the ink jet device may eliminate the contaminant inside of the head part 1 by the cleaning water. The cleaning water flows by hydraulic pressure in the cleaning water supplier 15 to remove the contaminant. However, the hydraulic pressure applied to the cleaning water supplier 15 might damage the head part 1, thus the strength of pressure that may be applied to the cleaning water supplier 15 is limited. Further, the pressure applied to the cleaning water supplier 15 can push out the contaminant only in a direction that the discharged material is sprayed. Because of the fact that the pressure applied for cleaning the head part 1 is provide only in the one direction that the discharged material is sprayed and that the strength is limited, the contaminant P resides behind at the corner inside of the chamber 5 and the collecting and delivering part 3. There is a problem because the remaining contaminant P, when being left alone for a long time, causes the head part 1 to clog, thus shortening the life span of the ink jet device and then forming a bad pattern.